A method for removing a mask in a selective area epitaxy process is provided. The method includes forming a first layer on a substrate and oxidizing the first layer. A patterned photoresist can be formed on the oxidized first layer. A portion of the oxidized first layer can then be removed using a wet chemical etch to form a mask. After removing the patterned photoresist a second layer can be epitaxially grown in a metal organic chemical vapor deposition (MOCVD) chamber or a chemical beam epitaxy (CBE) chamber on a portion of the first layer exposed by the mask. The mask can then be removed the mask in the MOCVD/MBE chamber. The disclosed in-situ mask removal method minimizes both the atmospheric exposure of a growth surface and the number of sample transfers.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for forming a semiconductor device comprising: forming an Al x O y layer on a first layer; patterning the Al x O y layer by forming a first region and a second region, wherein a thickness of the second region is greater than a thickness of the first region; placing the patterned Al x O y layer disposed on the first layer in a growth chamber; removing the first region of the Al x O y layer to expose a first portion of the first layer; epitaxially growing a second layer on the exposed first portion of the first layer; and removing the second region of the Al x O y layer to expose a second portion of the first layer within the growth chamber.
2. The method of claim 1 wherein the first layer comprises GaAs.
3. The method of claim 1 , wherein the second layer comprises GaAs.
4. The method of claim 1 , further comprising forming a third layer over the second layer and the exposed second portion of the first layer.
5. The method of claim 4 , wherein the third layer comprises GaAs.
6. The method of claim 1 , wherein the step of removing the first region of the Al x O y layer to expose the first portion of the first layer comprises exposing the first region to a carrier gas comprising hydrogen at a temperature of about 900°.
7. The method of claim 1 , wherein the step of forming an Al x O y layer on the first layer comprises oxidizing an AlGaAs layer.
8. The method of claim 1 , wherein the step of pattering the Al x O y layer by forming a first region and a second region comprises: depositing a photoresist layer on the Al x O y layer; patterning the photoresist layer; and forming the first region by etching the Al x O y layer using a wet chemical etch comprising HCl.
9. The method of claim 1 , wherein the step of removing the second region of the Al x O y layer within the growth chamber comprises exposing the second region of the Al x O y layer to HCl in a carrier gas comprising hydrogen.
10. The method of claim 1 , wherein epitaxially growing a second layer comprises a growth rate of about 7 Å/sec or less.
11. The method of claim 1 , wherein the step of removing the second region of the Al x O y layer within the growth chamber is conducted at a temperature of 550° C. or higher.
12. The method of claim 1 , wherein the step of removing the second region of the Al x O y layer within the growth chamber comprises stabilizing a temperature in the growth chamber to about 300° C. and providing an AsH 3 overpressure.
13. The method of claim 2 , wherein the GaAs layer is disposed on a substrate comprising GaAs ( 100 ).
14. A method for removing a mask in a selective area epitaxy process comprising: forming a first layer on a substrate; forming an Al x O y layer on the first layer; patterning the Al x O y layer by forming a first region and a second region, wherein a thickness of the second region is greater than a thickness of the first region; placing the patterned Al x O y layer disposed on the first layer in a growth chamber; forming a mask by exposing the patterned Al x O y layer to a hydrogen flow at about 900° C., wherein the hydrogen flow removes the first region of the Al x O y layer to expose a first portion of the first layer; epitaxially growing a second layer on the exposed first portion of the first layer; and removing the mask to expose a second portion of the first layer by introducing into the growth chamber an etchant comprising HCl in a hydrogen carrier gas.
15. The method of claim 14 , wherein the step of forming an Al x O y layer on the first layer comprises oxidizing the first layer at a temperature of about 425° C. or more.
16. The method of claim 14 , wherein the step of forming a mask by exposing the patterned Al x O y layer to a hydrogen flow at about 900° C. comprises an exposure time of about 5 minutes or more.
17. The method of claim 14 , wherein the step of epitaxially growing a second layer on the exposed first portion of the first layer comprises selective area epitaxy growth of GaAs at a rate of about 4 Å/sec.
18. A semiconductor device formed by a method comprising: forming an Al x O y layer on a first layer; patterning the Al x O y layer by forming a first region and a second region, wherein a thickness of the second region is greater than a thickness of the first region; placing the patterned Al x O y layer disposed on the first layer in a growth chamber; forming a dielectric mask by removing the first region of the Al x O y layer to expose a first portion of the first layer; epitaxially growing a second layer on the exposed first portion of the first layer; and removing the second region of the Al x O y layer to expose a second portion of the first layer using an in-situ etch.
19. The method of claim 18 , wherein the first layer comprises (001) oriented GaAs.
20. The method of claim 18 , wherein the second layer comprises GaAs.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
January 6, 2006
October 30, 2007
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